The stacked OLED (SOLED): a new type of organic device for achieving high-resolution full-color displays

We describe a novel organic light-emitting device (OLED) in which color, grey scale and intensity can be independently achieved. The device consists of three separately contacted, red-, green- and blue-emitting OLEDs placed in a vertical stack and separated by transparent, conducting electrodes. The stacked OLED (or SOLED) is shown to efficiently generate a high-intensity optical output whose color is a linear superposition of spectra of the individual emitting elements in the device. Optical microcavity effects are found to distort the output spectrum in non-optimized SOLEDs. To our knowledge, the SOLED architecture provides the highest efficiency and resolution, as well as the simplest means for fabricating full-color displays based on small molecular weight organic materials demonstrated to date. (C) 1997 Elsevier Science S.A.